To examine whether urinary nerve growth factor (NGF) could serve as a biomarker for interstitial cystitis/painful bladder syndrome (IC/PBS), we conducted a comprehensive meta-analysis of 9 studies. Among the studies considered, patients with IC/PBS had higher urinary NGF and NGF/Cr levels compared to those of healthy people (SMD = 1.94, 95%CI = 0.79–3.08, P = 0.0009 and SMD = 1.79, 95%CI = 0.65–2.93, P = 0.002, respectively). In addition, there was a significant difference between patients with IC/PBS and patients with overactive bladder (OAB) symptoms with respect to the urinary NGF and NGF/Cr levels (SMD = −0.62, 95%CI = −1.00–−0.24, P = 0.001 and SMD = −0.70, 95%CI = −1.01–−0.39, P<0.0001, respectively). Furthermore, patients had a significantly lower urinary NGF level after successful treatment (SMD = 1.74, 95%CI = 0.32–3.17, P = 0.02). In conclusion, urinary NGF could be a useful biomarker for the diagnosis of OAB, a urinary biomarker for the differential diagnosis of IC/PBS and OAB (when a critical urinary NGF or NGF/Cr level is needed), and a predictive biomarker to help guide treatment.